The present invention relates to a semiconductor device constituted by stacking a plurality of semiconductor layers in which semiconductor elements are formed.
Recently, a three-dimensional SOI (Silicon On Insulation) device has been widely developed so as to realize a highly integrated multifunctional semiconductor device. In this technique, a monocrystalline silicon layer is formed on an amorphous insulating film of a semiconductor substrate surface, and semiconductor elements are formed using the monocrystalline layer, thereby to obtain a three-dimensional layer structure. Such a technique is described in, for example, an article "3-Dimensional LSI Emerging As High Integration/Multi-Function Device" of "NIKKEI ELECTRONICS", Oct. 7, 1985.
Nevertheless, development of the SOI technique has only just begun, and many drawbacks remain, with regard to its practical use. The main drawbacks are as follows:
.circle.1 Since a plurality of semiconductor and insulation layers of different properties are stacked, and the stacked semiconductor layers are converted to monocrystalline layers by means of a high-temperature process, stress acting on the semiconductor layers becomes so great that cracks tend to occur in these layers, with the result that there may be a deterioration in the electrical properties thereof;
.circle.2 Since the layers are formed in close contact with each other, the heat-dissipation efficiency is therefore low, i.e., heat tends to be retained inside.
Further, with the present semiconductor manufacturing technique, it is impossible to stack semiconductor materials other than silicon.